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Use of marine condensers in a refrigeration system
Shell and tube type marine condensers :
Marine condensers are generally of the shell and tube type, designed for high
pressures. There may a few coil-in-casing or other types still in use. The coolant
passes through the tubes with refrigerant condensing on the outside.
Condenser tubes provide heat transfer surfaces in which heat from the hot
refrigerant on the outsides of the tubes passes through the walls of the tubes to
the cooling water inside. Sea water is the usual cooling medium for shell and
tube condensers, but fresh water from central cooling systems is increasingly
being used. The refrigerant vapour is cooled first to saturation point, then to
the liquid state.
The design of condensers is largely dictated by the quantity
and cost of the circulating water, and, where water is plentiful as at sea, a large
number of short circuits may be used, to keep pressure drop to a minimum.
Water velocity is restricted to prevent erosion of the tubes, usually being kept
below 2.5 m/s.
Marine condensers are very susceptible to corrosion and much research has
been done to lengthen their useful life. With halogenated hydrocarbon
refrigerants, the use of aluminium brass or cupro-nickel tubes and brass tube
plates is acceptable and has reduced the rate of corrosion on the sea-water side.
Refrigerant 717 (ammonia) tends to corrode these materials however, and it
has been found necessary to use stainless steel or even bimetallic tubes and clad
tube plates, with ferrous metal being in contact with the refrigerant, and
non-ferrous with the sea water. The use of sacrificial anodes in the water ends
of the condensers is common and sometimes a short length of ungalvanized
pipe is fitted between the condenser and the galvanized steel pipe system.
The use of fresh water from a central cooling system closed circuit, avoids
the problem of sea-water corrosion.
Refrigeration system components Centrifugal,reciprocating, or screw compressors. Modern Shell and tube type condensers.Various refrigerant types, refrigerant flow control valves & Ancillary fittings etc.....
Modern refrigerants for cargo ships
In all refrigeration, heat is collected in a suitable fluid and this fluid is removed from the space substance being cooled carrying the heat with it. Such fluid known as refrigerant. All refrigerants using on board might be sub-divided into primary and secondary refrigerants.....
Choice of refrigerants
Theoretically, almost any liquid can be used as a refrigerant if its pressure/temperature relationship is suitable for the conditions. Although no perfect refrigerant is known, there are certain factors which determine a refrigerant's desirability for a particular duty and the one selected should .....
Cargo refrigeration procedure Refrigerated cargo vessels usually require a system which provides for various spaces to be cooled to different temperatures. The arrangements adopted can be considered in three parts: the central primary refrigerating plant, the brine circulating system, and the air circulating system for cooling the cargo in the hold.....
How to troubleshoot refrigeration system faults
It is important that gas losses are minimized in systems. Gas used in this system is both expensive and a danger to health. The system is therefore to be kept in an absolutely gas-tight condition. On no account should the refrigerant be blown off to atmosphere. Before carrying out repairs the refrigerant should be pumped down to the liquid receiver or the condenser. The remaining gas should be vented off and the area well ventilated.....
Safety precautions for refrigeration plant and refrigerated compartments Adequate information should be available on each vessel, laying down the operation and maintenance safeguards of the refrigeration plant, the particular properties of the refrigerant and the precautions for its safe handling.....
Reefer container Individual containers with their own refrigeration plant are connected to the 440 or 220 a.c. sockets provided on deck. Systems designed for the cooling of refrigerated containers employ trunkings arranged so that containers stowed in stacks between built-in guide rails, can be connected to the suction and delivery air ducts of the ship's
refrigeration plant by bellows pieces operated pneumatically......
Marine machineries - Useful tags
Marine diesel engines ||Steam generating plant ||Air conditioning system ||Compressed air ||Marine batteries ||Cargo refrigeration ||Centrifugal pump ||Various coolers ||Emergency power supply ||Exhaust gas heat exchangers ||Feed system ||Feed extraction pump ||
Flow measurement || Four stroke engines || Fuel injector || Fuel oil system || Fuel oil treatment ||Gearboxes || Governor ||
Marine incinerator ||
Lub oil filters ||
MAN B&W engine ||
Marine condensers ||
Oily water separator ||
Overspeed protection devices ||
Piston & piston rings ||
Crankshaft deflection ||
Marine pumps ||
Various refrigerants ||
Sewage treatment plant ||
Starting air system ||
Steam turbines ||
Steering gear ||
Sulzer engine ||
Turbine gearing ||
Two stroke engines ||
UMS operations ||
Drydocking & major repairs ||
Critical machinery ||
Deck machineries & cargo gears
|| Control and instrumentation
||Engine room safety ||
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